PNU-95666E, a D2 agonist anticipated to minimize Parkinson symptoms, will be used for the first clinical study in this patient population. The study will explore saftey, tolerance to dose escalation, pharmaco-dynamic response, and pharmacokinetic profiles in 40 patients nationally. Randomization will be equally divided between 4 treatment arms. Study endpoints will be evaluated to establish a dose range from which to predict response to PNU-95666E and design subsequent dose-response studies. Recruitment ongoing.